Just curious why the default in this release is Glide rather than OpenGL. Shouldn't OpenGL at this point be higher quality and less buggy, since you can run it without a wrapper? I know Interstate '76 in comparison looks best in Glide, but AFAIK, SiN does not have any Glide-specific effects. I've tried it both ways, and it looks about the same to me. Please let me know if I'm wrong about this.

Also, what does the program "player.exe" do exactly? This seems to be something GOG added. I'm not sure what it does or why it's needed. I tried deleting it to see what would happen - on startup I get two errors about not finding "player.exe," but after that the game seems to work fine without it.

AFAIK, with OpenGL you need the Extension Limit fix if you use nvidia graphics drivers.

Maybe I was doing something wrong when I had Default OpenGL selected, but in my opinion that renderer had muddier textures than the Direct3D - or whatever they call it in SiN - (3DFX?). So for me at least, Direct3D looked good but had a choppy frame rate when certain dynamic lighting occurred; Default OpenGL was the smoothest but looked worse.
Best thing to do, I found, was to leave the in-game video settings alone and setup the visual side of things using the nglide config within the SiN folder.

Glide, to me looks better than OpenGL. I'm fairly sure the lighting is superior.